Hematologic malignancies such as multiple myeloma, adult T cell leukemia and malignant lymphoma are often complicated with bone lesions and/or hypercalcemia. The abnormal bone metabolism in these diseases are modified by co-existing cachexia, malnutrition, sex hormone deficiency and abnormal parathyroid function or by chemotherapy in a complex manner. Metabolic bone markers are not only clinically useful for evaluation and diagnosis of such bone abnormalities but may also be used to monitor the disease activity itself, particularly in multiple myeloma which almost inevitably involves bone destructive lesions.